In a dry process for manufacturing a spun lace nonwoven fabric (or fiber-interlaced nonwoven fabric), a fibrous web is formed by one or more stages of carding machines and is conveyed to a fiber interlacing step. At this fiber interlacing step, the fibrous web is conveyed by a wire conveyor band of a predetermined mesh so that water jets are applied to the fibrous web to interlace the fibers thereby forming a nonwoven fabric. This nonwoven fabric thus formed at the fiber interlacing step is further conveyed to and dried at a drying step.
In a wet process for manufacturing a spun lace nonwoven fabric of the prior art, on the other hand, at the wet forming step, raw material fibers are supplied together with water onto a net-shaped wire conveyor band of a predetermined mesh to form a fibrous web. A felt conveyor band is then contacted by the wire conveyor band so that the fibrous web over the wire conveyor band is transferred to the felt conveyor band due to the difference in the surface roughness between the wire and felt conveyor bands. By this felt conveyor band, the fibrous web is conveyed to a fiber interlacing step.
At the fiber interlacing step, there is provided a wire conveyor band running on a plurality of rolls, and the fibrous web is transferred from the felt conveyor band to the wire conveyor band. Water jets are then applied to the fibrous web being conveyed over the wire conveyor band, so that the fibers of the fibrous web are interlaced to form the nonwoven fabric. This nonwoven fabric is conveyed from the fiber interlacing step to the drying step where it is dried.
The dry process for manufacturing the spun lace nonwoven fabric cannot increase the treating rate more than the fiber supplying rate at the carding machine. As a result, the speed of manufacturing the nonwoven fabric as a whole is lowered and limited at about 100 m per minute at most, so that the dry process is inferior in productivity. On the other hand, the dry process cannot manufacture a soft, nonwoven fabric because the fibers which are treated by the carding machine become relatively thick (about 1.5 to 3 deniers).
In this respect, the wet spun lace nonwoven fabric manufacturing process (wet process) can form nonwoven fabric having fibers as thin as about 0.1 to 0.5 deniers so that it can manufacture a nonwoven fabric having softness such as for use on glass plates or lenses, or as wet tissues.
In the wet spun lace nonwoven fabric manufacturing processes of the prior art, however, the fibrous web is formed by the wet forming machine and conveyed by the felt conveyor band to the fiber interlacing step, at which water jets are applied. As a result, this complicates the facilities and creates a longer manufacturing line, thereby requiring a larger space for installing the facilities.